Abstract:【Objective】This study aims to find an ideal and effective bud dormancy break method for Shine Muscat grapes and to explore the gene express level of bud dormancy break by using H2CN2 and ‘lime sulfur mixture+ACC’.【Methods】By using the winter buds of 'Shine Muscat' grapes as material, we studied the effects of different bud dormancy breaking treatments in the endodormancy stage and paradormancy stage on germination rate, flowering rate and inflorescence quality, and screened the possible effects on grape winter buds through transcriptome sequencing, and the key genes that may affect grape winter bud germination were screened through transcriptome sequencing.【Results】The winter buds on the isolated branches of the Shine Muscat grape in the endodormancy stage were treated with cyanamide (T1) and ‘lime sulfur mixture + ACC’ (T2) at one month before germination stage. The results showed that the T1 treatment sprouted earliest, followed by the T2 treatment, and finally the CK group. The overall germination speed of each treatment showed a trend of slow first and then fast. In terms of germination rate, the germination rate of T2 treatment was the highest at 85.80%, followed by T1 treatment and CK groupwith germination rates of 81.48% and 66.05% respectively. And the germination rates after T1 treatment and T2 treatment were significantly higher than those of the CK group. The growth and development dynamics of winter buds on isolated branches were observed, and it was found that the winter buds treated with T1 and T2 all grew 2 to 3 new leaves on March 21, 2022. T1 treatment sprouts the earliest, T1 and T2 sprout more neatly; In the Control group, 2 to 3 new leaves were grown on April 2, 2022, and the growth was relatively slow and the sprouts were irregular. In August 2022, cyanamide treatment (H2CN2, T1) and ‘lime sulfur mixture + ACC’ treatment (T2) was carried out on the winter buds of Shine Muscat grapes in the paradormancy stage, the results showed that the T1 treatment sprouted earliest, followed by the CK group, and T2 treatment. The germination speed of among each treatment showed a trend of first slow and then fast as well. The germination rate of T2 treatment was the highest, which was 69.70%, followed by T1 treatment and CK group, with germination rates of 65.66% and 41.41% respectively. The germination rate of T1 and T2 treatment was significantly higher than that of the CK group. In February 2023, by treating the winter buds of Shine Muscat grapes in the endodormancy stage with cyanamide (T1) and ‘lime sulfur mixture + ACC’ (T2), The results showed that the T2 treatment had the highest germination rate of 97.22%, followed by the T1 treatment and CK group, with the germination rates of 96.43% and 76.19% respectively. From 25 days post treatment to the end of counts, the germination rate of T1 and T2 treatments shows significantly higher level than the CK group. There is no significant difference in the inflorescence rate under T1 and T2 treatments compared with the CK group. At the same time, and the length of inflorescence was not influenced as well; The growth status of the branches was observed, and the results showed that, compared with the CK group, the leaves grew fastest after the T1 treatment on April 3, 2023, followed by the T2 treatment. On April 29, 2023, the leaf growth rate, leaf size, and internode length after T1 and T2 treatments had no significant impact compared with the CK group. Six samples in the endodormancy stage (winter buds were collected at 24 h and 72 h after CK group, T1 treatment, and T2 treatment) and six samples in the paradormancy stage (CK group, T1 treatment, and T2 treatment were collected at 24 h and 72 h after winter bud) for transcriptome analysis, a total of 4399 differentially expressed genes were obtained by using |log2fold changes|≥1, FDR＜0.01 as the filtering parameters, 4399 significantly different genes (DEGs) can be divided into 8 clustering groups. Among all the DEGs, in W-CK-72 samples and W-HC-72 samples of the endodormancy stage samples, 10 genes were annotated as transcription factor coding genes, which were all related to bud germination. There transcription factors of them were up-regulated and 7 transcription factors were up-regulated. In addition, 10 genes were annotated as being involved in the biosynthesis or signal transduction processes of hormones such as auxin, gibberellins, abscisic acid, and brassinosteroids; Five gene were related to the ABA signaling pathway, among them, PYL4 and PP2C25 genes shows up-regulated expression, while PP2C24, PP2C8 and PP2C37 genes have down-regulated expression; The SAPK2 gene which related to the Snrk2 family was down regulated expression; The remaining differential genes screened are related to oxidative stress, glutathione S-transferase, etc. These candidate genes may affect grape bud germination by participating in hormone signaling, oxidative stress and other pathways.【Conclusion】The mixed solution of ‘lime sulfur + ACC’ is a safe and effective agent for breaking the bud dormancy of 'Shine Muscat' grapes. Genes such as hormone signaling and oxidative stress may respond to the dormancy release process.
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